1. Field of the Invention
The present disclosure relates to illumination systems, and more specifically, to an illumination system that selectively provides either of a collimated light beam or a convergent light beam. The system is particularly well-suited where illumination is desired for both total internal reflection fluorescent (TIRF) microscopy and fluorescence recovery after photobleaching (FRAP) or photoactivation experiments.
2. Description of the Related Art
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, the approaches described in this section may not be prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
A fluorescence microscope is a light microscope used to study properties of organic or inorganic substances using the phenomena of fluorescence and phosphorescence instead of, or in addition to, reflection and absorption. In some cases, for example, fluorescence recovery after photobleaching (FRAP), an image plane of a microscope is best illuminated by a converging beam of light. In other cases, for example, total internal reflection fluorescence (TIRF), the image plane is best illuminated by a collimated beam of light.